The long-range goal of the Program Project will continue to be to provide a thorough understanding of the complex regulation of hormone secretion by the adenohypophysis. For a number of years we have been carrying on a multifaceted attack on the neural control of the gonadotropins and prolactin. These interrelating projects have been combined in this Program Project grant. Studies will be conducted to delineate further the pathways in the CNS involved in the regulation of gonadotropin and prolactin secretion & to evaluate putative transmitters involved in release of the releasing and inhibiting hormones which control the release of the pituitary hormones. The effects of steroids and other agents on the responsiveness of the pituitary to LH-releasing hormone (LRH) and the mechanism of action of the releasing and inhibiting hormones on the gland will be examined further. Further studies on the postulated FSH-releasing factor, the hypothalamic factors which alter prolactin release and a postulated hypothalamic inhibitor of gonadotropin release will be carried out. A detailed study of the neuroendocrinology of puberty and sexual development is in progress. The electrical activity and chemical sensitivity of identified hypothalamic units which project to the median eminence are being studied to characterize the behavior of these presumed neurosecretory elements.